The present invention relates to a door lock, and more particularly to a clutch for an electronic door lock.
Electronic door locks typically include a mechanical lock and an electronic control for authorizing the use of the mechanical lock. A portion of the mechanical lock secures the door to the door frame. The electronic control may include, for example, a reader that permits data to be read from a coded medium such as a magnetic card, proximity card, or memory key. When a card or key with valid data is presented to the electronic control, the control permits an outer handle or door knob to operate a shaft of the mechanical lock by actuating a prime mover to either release a latch that was preventing the handle or knob from turning, or engage a clutch that couples a shaft of the handle or knob to the shaft of the mechanical lock.
The mechanical lock and electronic control components (including the prime mover and latch/clutch) of electronic door locks are commonly powered by alkaline batteries which typically have a service life of between about two to three years. This limited battery service life necessitates changing the batteries several times over the service life of the door lock; a process that increases the operating costs of businesses which employ the electrical locks. One of the keys for extending battery life and reducing business operating costs is developing a more efficient clutch because the clutch in an electronic door lock typically consumes about 70 percent of the energy the entire lock system utilizes.